Continuous harvest over an annual period is a common assumption of continuous biomass dynamics models (CBDMs); however, fish are frequently harvested in a discrete manner. We developed semidiscrete biomass dynamics models (SDBDMs) that allow discrete harvest events and evaluated differences between CBDMs and SDBDMs using an equilibrium yield analysis with varying levels of fishing mortality (F)...

#465 Summary: The problem the economists in the field of renewable resources face is that of determining and recommending the harvest intensity that will maximize the economic value to the consuming society and also maximize the producers' surplus at a level of production in perpetuity. The optimal control theoretic approach was employed in this paper to theoretically answer this problem within...

Over 100 native herbaceous forest perennials are harvested in the United States. Management of these populations for continued survival requires information on the long-term effects of varied harvesting levels on populations of forest perennials. Allium tricoccum Ait. is a species that is harvested throughout its range for its edible bulb. We examined the recovery of A. tricoccum populations ov...

Turbidity regimes vary dramatically among small streams in north coastal California. In an analysis of turbidity data from 27 small streams in the region, turbidity at the 10-percent exceedence level ranged from 3 to 116 formazin nephelometric units (FNU) for the 2005 wet season, translating to 1.7 to 65 days above an oft-cited biological threshold of 25 FNU. Watersheds draining to the streams ...

• Incorporation of price risk into decision making process is fundamentally important. Both historical price information and projected future price come into play. Due to the usual lengthy gap between planning and harvest, expected price is the dominant factor. Given that many agricultural commodities are represented in the future and option markets, it is a common practice to infer the collect...

Knowledge of the relationship between waterfowl hunters and harvest levels may better inform harvest management decisions. We examined frequency of different sizes of daily harvests among duck hunters, and hunters’ contributions to duck harvest in the Central Flyway from 1975–1984, 1988–1993, and 2002–2011 using the U.S. Fish and Wildlife Service’s Parts Collection Survey. We stratified hunters...

In northern Australia, traditional indigenous hunting of turtle and dugong species continues to be a vital part of cultural practice, yet daily attracts media controversy. Both turtle and dugong species have experienced documented declines in the last two decades. A community hunting planning and management initiative in Hopevale community, (now in the process of implementation) was established...

The yield estimation models on a regional scale are generally constrained by the lack of spatially distributed information on major environmental. The utilization of remote sensing data with various spatial and temporal resolutions can settle this problem. The NDVI, which retrieved from satellite remote sensing, was adopted to forecast winter wheat yields in this paper. There are two key steps ...